### Commercial **Airplanes** 

# 737

Service Bulletin **ALERT Number:**  **737-57A1326** Original Issue: September 22, 2015 ATA System: 5711 **SUBJECT:** WING - Wing Spars - Inspection of Upper Wing Skin at Rear Spar, Wing Buttock Line

157 Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15 CFR 300-774). An export license may be required before it is used for development, production or use by foreign persons from specific countries. The controller of this data has the individual responsibility to abide by all export laws. 9E991 ECCN: 

## BOEING PROPRIETARY, CONFIDENTIAL AND/OR TRADE SECRET Copyright © 2015 Boeing. Unpublished Work. All Rights Reserved. Treatment of this document and its content is governed by contract with Boeing. Rights to use this document are licensed on a per aircraft basis and such rights may not be transferable. For more information, contact The Boeing Company. Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner, BBJ, DC-8, DC-9, DC-10, KC-10, KC-46, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8, Poseidon and Boeing liveries are all trademarks owned by The Boeing Company; and no trademark license is granted in connection with this document unless provided in writing by Boeing.

Original Issue: September 22, 2015 737-57A1326 1of39 2.0Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 2of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**

BLANK PAGE**Table of Contents**

Summary

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1. PLANNING INFORMATION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 A. Effectivity

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1. Airplanes

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2. Spares Affected

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 B. Concurrent Requirements

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 C. Reason

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 D. Description

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 E. Compliance

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 F. Approval

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 G. Manpower

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 H. Weight and Balance Changes

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 I. Electrical Load Data

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 J. References

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 1. Existing Data:

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2. Data Supplied with this Service Bulletin:

. . . . . . . . . . . . . . . . . . . . . . . . . . . 26 3. Installation Drawings Used in the Preparation of this Service Bulletin:

. . . . . . . . . . . 26 K. Publications Affected

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 L. Interchangeability and Intermixability of Parts

. . . . . . . . . . . . . . . . . . . . . . . . . . . 27 M. Software Accomplishment Summary

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2. MATERIAL INFORMATION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 A. Material - Price and Availability

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 B. Industry Support Information

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 C. Parts Necessary for Each Airplane

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 1. Kits/Parts

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2. Parts and Materials Supplied by the Operator

. . . . . . . . . . . . . . . . . . . . . . . . 29 3. Parts Modified and Reidentified

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 4. Parts Removed and Not Replaced

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 D. Parts Necessary to Change Spares

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 E. Special Tooling - Price and Availability

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 F. Special Tooling Necessary to do this Service Bulletin

. . . . . . . . . . . . . . . . . . . . . . . 29 3. ACCOMPLISHMENT INSTRUCTIONS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 A. GENERAL INFORMATION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 B. WORK INSTRUCTIONS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 FIGURE 1: HFEC INSPECTION OF INSPAR UPPER SKIN AT REAR SPAR, WBL 157[Group 1,

Configuration 2, 5]

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 FIGURE 2: HFEC INSPECTION OF INSPAR UPPER SKIN AND REPAIR DOUBLER AT REAR SPAR,

WBL 157[Group 1, Configuration 3, 6]

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 FIGURE 3: HFEC AND LFEC INSPECTION OF INSPAR UPPER SKIN, REPAIR DOUBLER, AND REPAIR

TRIPLER AT REAR SPAR, WBL 157[Group 1, Configuration 4, 7]

. . . . . . . . . . . . . 38

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 3of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 4of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**

BLANK PAGE

### Commercial **Airplanes** 

# 737

Service Bulletin **ALERT Summary**  **Number: 737-57A1326**  Original Issue: September 22, 2015 ATA System: 5711 **SUBJECT:** WING - Wing Spars - Inspection of Upper Wing Skin at Rear Spar, Wing Buttock Line

157 THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH 1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OWNER. **CONCURRENT REQUIREMENTS** None. **BACKGROUND** For airplanes that have not been inspected using the High Frequency Eddy Current (HFEC) open hole inspection in accordance with Service Bulletin (SB)737-57-1318, this SB gives instructions to do inspections for any crack in the inspar upper skin area near the rear spar at Wing Buttock Line (WBL) 157 until SB737-57-1318is accomplished. For an airplane that has not been inspected using the HFEC open hole inspection in accordance with SB737-57-1318, if the inspections in this service bulletin are not done, a crack in the upper chord and skin can grow undetected and result in the inability of the structure to carry limit load or result in a fuel leak and could prevent a continued safe flight and landing. While doing SB737-57-1318, an operator discovered a crack in the inspar upper skin at WBL 157 just forward of the rear spar on the right wing. The crack measured 2.375 inches long. Two additional cracks were found in the skin at two holes common to the rear spar in the same area. Subsequent inspections per SB737-57-1318 revealed that the rear spar upper chord was almost completely severed. Further inspections per SB737-57-1318 revealed that the left rear spar upper chord was completely severed. Web cracks were also discovered on both wings. The airplane was a 737-300 with 64,095 flight hours and 51,548 flight cycles. The airplane was within the 4,500 flight cycle grace period allowed by SB737-57-1318. The inspections in this SB will ensure there is no undetected crack in the inspar upper skin area near the rear spar at WBL 157 prior to the accomplishment of the inspections required by SB737-57-1318

.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 5of39This table is provided to operators for planning purposes only. Refer to the applicable sections for more

information.
**Reference Affected**  **Planning Data** Paragraph 1.A.2., Spares Affected No Spares Affected Paragraph 1.E., ComplianceandParagraph 1.F., Approval Yes AD Related Paragraph 1.H., Weight and Balance Changes No Weight and Balance Change Paragraph 1.I., Electrical Load Data No Electrical Load Changed Paragraph 1.K., Publications Affected No Publications Affected Paragraph 1.K., Publications Affected No Airplane Flight Operations Affected (Flight CrewOperations Manual and/or FAA Approved Airplane Flight Manual) Paragraph 2.C.1., Kits/Parts No Kits/Parts Required Paragraph 2.C.2., Parts and Materials Supplied by the Operator No Operator Supplied Parts/Material Paragraph 2.F., Special Tooling Necessary to do this Service Bulletin No Special Tooling Required

**ACTION** Airplanes that have not been inspected using the HFEC open hole inspection in accordance with SB737-57-1318, do an eddy current inspection for any crack in the inspar upper skin area near the rear spar at WBL 157. If a repair has been installed, do an eddy current inspection for any crack in the repair parts. If any crack is found, do the HFEC open hole inspection in accordance with SB737-57-1318and contact Boeing for repair instructions and do the repair. **EFFECTIVITY** All 737-100, 737-200, 737-200C, 737-300, 737-400, and 737-500 airplanes. Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplanes. **COMPLIANCE** The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin mandatory. Refer toParagraph 1.E., Compliance

. **INDUSTRY SUPPORT INFORMATION** At the time of release of this service bulletin, warranty remedies have not been determined. A subsequent revision or Information Notice will address the warranty remedies available, if any.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 6of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT MANPOWER** 

Refer toParagraph 1.G., Manpower

. **MATERIAL INFORMATION** None.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 7of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 8of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**

### Commercial **Airplanes** 

# 737

Service Bulletin **ALERT Number:**  **737-57A1326** Original Issue: September 22, 2015 ATA System: 5711 **SUBJECT:** WING - Wing Spars - Inspection of Upper Wing Skin at Rear Spar, Wing Buttock Line

157 THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH 1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OWNER. **1. PLANNING INFORMATION A.**  **Effectivity** 1. Airplanes This service bulletin is applicable to line numbers 1 to 3132 in 1 Group. The Variable Numbers and Group Information for the applicable airplanes is given below. Refer toService Bulletin Index D6-19567Part 3 for Airplane Variable Number, Line Number, and Serial Number data.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 9of39**DESCRIPTION CONFIGURATION**  **GROUP** 737-100, 737-200, 737-200C, 737-300, 737-400, and 737-500 airplanes Line Numbers 1 to 3132. - 1
Airplanes that have been inspected using the High Frequency Eddy Current (HFEC) open hole inspection in accordance with Service Bulletin 737-57-1318. 1

Airplanes that have been inspected using only the HFEC surface

inspection in accordance with Service Bulletin 737-57-1318 and do not have a repair doubler or repair tripler in the inspection area. 2

Airplanes that have been inspected using only the HFEC surface

inspection in accordance with Service Bulletin 737-57-1318 and have a repair doubler in the inspection area common to the rear spar chord fasteners that extends to the aft edge of the inspar skin similar to repair drawing 65C30105. 3

Airplanes that have been inspected using only the HFEC surface

inspection in accordance with Service Bulletin 737-57-1318 and have a repair tripler and a repair doubler in the inspection area common to the rear spar chord fasteners that extends forward to the adjacent stringer similar to repair drawing 65C30113. 4

Airplanes that have not been inspected in accordance with Service

Bulletin 737-57-1318 and do not have a repair doubler or repair tripler in the inspection area. 5

Airplanes that have not been inspected in accordance with Service

Bulletin 737-57-1318 and have a repair doubler in the inspection area common to the rear spar chord fasteners that extends to the aft edge of the inspar skin similar to repair drawing 65C30105. 6

Airplanes that have not been inspected in accordance with Service

Bulletin 737-57-1318 and have a repair tripler and a repair doubler in the inspection area common to the rear spar chord fasteners that extends forward to the adjacent stringer similar to repair drawing 65C30113. 7

Airplane Models: 737-100,737-200,737-200C,737-300,737-400,737-500 **Group Variable Number**  1 PA001 - PA022 1 PA099 1 PA231 - PA232

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 10of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group**  **Variable Number** 1 PC001 - PC005 1 PG001 - PG075 1 PG199 1 PG201 - PG230 1 PG251 - PG255 1 PG271 - PG279 1 PG301 - PG314 1 PG331 - PG332 1 PG351 - PG356 1 PG375 1 PG401 - PG403 1 PG431 - PG442 1 PG471 - PG475 1 PG501 - PG505 1 PG571 - PG586 1 PG621 - PG630 1 PG651 - PG652 1 PG701 - PG705 1 PH001 1 PH011 - PH013 1 PH021 - PH024 1 PH701 - PH715 1 PH731 - PH732 1 PH741 - PH743 1 PJ001 - PJ009 1 PJ031 - PJ032 1 PJ071 - PJ072 1 PJ101 - PJ119 1 PJ201 - PJ219 1 PJ301 - PJ302 1 PJ551 - PJ561 1 PJ601 - PJ615 1 PJ811

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 11of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group**  **Variable Number** 1 PJ816 - PJ817 1 PK026 - PK029 1 PK041 - PK053 1 PK061 - PK070 1 PK081 - PK082 1 PK091 - PK099 1 PK101 - PK103 1 PK111 - PK120 1 PK141 - PK146 1 PK201 - PK204 1 PK211 - PK223 1 PK231 - PK241 1 PK251 - PK258 1 PK271 - PK274 1 PK281 - PK289 1 PK291 1 PK301 - PK318 1 PK341 1 PK351 - PK361 1 PK391 1 PK431 - PK433 1 PK451 - PK452 1 PK461 - PK469 1 PK495 1 PK501 - PK504 1 PK511 - PK515 1 PK519 1 PK521 - PK528 1 PK541 - PK565 1 PK581 1 PK591 - PK599 1 PK601 - PK617 1 PK621 - PK637

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 12of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group**  **Variable Number** 1 PK641 - PK642 1 PK661 - PK666 1 PK671 - PK681 1 PK691 - PK697 1 PK711 - PK716 1 PK731 - PK765 1 PK771 - PK779 1 PK801 - PK804 1 PK819 - PK827 1 PK830 1 PK861 - PK863 1 PK871 - PK874 1 PK881 - PK884 1 PK901 - PK938 1 PK971 - PK974 1 PL001 - PL028 1 PL061 1 PL081 1 PL101 - PL113 1 PL151 1 PL171 - PL172 1 PL201 - PL203 1 PL221 1 PL401 - PL417 1 PL421 1 PL441 1 PL451 - PL456 1 PL471 1 PL491 1 PL501 - PL506 1 PL551 - PL562 1 PL581 1 PL601 - PL603

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 13of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group**  **Variable Number** 1 PL611 1 PL621 - PL626 1 PL631 - PL632 1 PL711 - PL712 1 PL716 - PL747 1 PL756 1 PL758 1 PL761 - PL770 1 PL781 - PL788 1 PL793 1 PL801 - PL803 1 PM001 - PM006 1 PM016 - PM017 1 PM021 - PM023 1 PM051 - PM066 1 PM101 - PM119 1 PM141 - PM142 1 PM171 1 PM181 1 PM251 - PM255 1 PM281 - PM283 1 PM381 - PM399 1 PM401 - PM417 1 PM541 - PM564 1 PN001 - PN002 1 PN021 - PN043 1 PN081 - PN086 1 PN101 - PN117 1 PN131 - PN163 1 PN401 - PN420 1 PN431 - PN433 1 PN451 - PN456 1 PN471 - PN474

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 14of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group**  **Variable Number** 1 PN481 1 PN491 - PN493 1 PN501 - PN502 1 PN511 - PN512 1 PN521 1 PP001 - PP054 1 PP101 - PP169 1 PP181 - PP199 1 PP201 - PP205 1 PP221 1 PP231 - PP243 1 PP281 - PP286 1 PP301 - PP305 1 PP351 - PP353 1 PP376 - PP384 1 PP391 - PP393 1 PP401 - PP440 1 PP471 - PP475 1 PP501 - PP522 1 PP631 - PP634 1 PP651 - PP652 1 PP671 - PP699 1 PP701 - PP733 1 PP771 - PP779 1 PP801 - PP808 1 PP821 - PP827 1 PP831 - PP848 1 PP851 - PP852 1 PP861 - PP877 1 PP891 - PP899 1 PP901 - PP936 1 PP946 - PP948 1 PP951 - PP952

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 15of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group**  **Variable Number** 1 PP961 - PP967 1 PP981 - PP991 1 PP993 1 PQ001 - PQ016 1 PQ026 - PQ041 1 PQ051 - PQ092 1 PQ101 - PQ199 1 PQ201 - PQ202 1 PQ221 - PQ237 1 PQ241 - PQ243 1 PQ251 - PQ267 1 PQ281 - PQ299 1 PQ301 - PQ307 1 PQ331 - PQ332 1 PQ341 - PQ348 1 PQ361 - PQ373 1 PQ391 - PQ395 1 PQ401 - PQ418 1 PQ421 1 PQ431 - PQ438 1 PQ447 - PQ448 1 PQ451 1 PQ454 1 PQ471 - PQ475 1 PQ479 - PQ481 1 PQ486 - PQ487 1 PQ491 - PQ493 1 PQ771 - PQ772 1 PQ791 - PQ793 1 PQ801 - PQ805 1 PQ931 - PQ935 1 PQ951 1 PQ971 - PQ997

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 16of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group**  **Variable Number** 1 PR001 - PR017 1 PR021 - PR034 1 PR041 - PR045 1 PR061 - PR072 1 PR077 - PR082 1 PR091 - PR092 1 PR096 1 PR101 1 PR121 - PR122 1 PR131 - PR132 1 PR141 - PR143 1 PR161 - PR172 1 PR181 1 PS601 - PS631 1 PS636 - PS638 1 PS641 - PS644 1 PS651 - PS657 1 PS666 - PS669 1 PS691 - PS692 1 PS701 - PS706 1 PS751 - PS799 1 PS811 1 PS836 - PS837 1 PS841 - PS846 1 PS851 - PS852 1 PS856 1 PS861 - PS863 1 PS866 - PS868 1 PS871 - PS874 1 PS896 - PS897 1 PS901 - PS941 1 PS956 - PS957 1 PS961 - PS963

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 17of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group**  **Variable Number** 1 PS971 - PS978 1 PT001 - PT015 1 PT021 - PT031 1 PT041 - PT064 1 PT101 - PT105 1 PT121 - PT138 1 PT146 - PT148 1 PT161 - PT170 1 PT181 - PT188 1 PT211 - PT220 1 PT295 1 PT301 - PT309 1 PT331 - PT360 1 PT381 - PT399 1 PT401 - PT438 1 PT501 - PT517 1 PT561 - PT565 1 PT581 - PT586 1 PT611 - PT621 1 PT641 - PT644 1 PT651 - PT656 1 PT671 - PT672 1 PT681 - PT685 1 PT701 - PT703 1 PT716 - PT717 1 PT721 - PT725 1 PT801 - PT834 1 PT851 - PT854 1 PT871 - PT886 1 PT901 - PT930 1 PT971 - PT973 1 PT981 - PT985 1 PT996

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 18of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group**  **Variable Number** 1 PU001 - PU025 1 PU301 1 PU311 - PU313 1 PV001 - PV055 1 PV201 - PV209 1 PV226 - PV229 1 PV231 - PV237 1 PV271 - PV272 1 PV281 - PV287 1 PV296 1 PV301 - PV302 1 PV351 1 PV356 - PV357 1 PW001 - PW054 1 PW061 - PW068 1 PW072 1 PW086 - PW088 1 PW091 - PW094 1 PW101 - PW102 1 PW106 1 PW111 - PW120 1 PW156 - PW157 1 PW161 - PW171 1 PW201 - PW252 1 PW261 - PW268 1 PW271 - PW276 1 PW278 1 PW281 - PW293 1 PW296 1 PW301 - PW327 1 PW401 - PW408 1 PW411 - PW418 1 PW421 - PW424

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 19of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group**  **Variable Number** 1 PW431 - PW435 1 PW441 - PW450 1 PW461 - PW467 1 PW501 - PW504 1 PW511 - PW522 1 PW524 - PW550 1 PW556 - PW557 1 PW561 - PW564 1 PW571 - PW576 1 PW591 - PW596 1 PW611 - PW622 1 PW631 - PW637 1 PW661 - PW662 1 PW681 - PW683 1 PW701 - PW702 1 PW711 - PW717 1 PW741 - PW742 1 PW761 1 PW771 1 PW831 1 PW851 - PW856 1 PX071 1 PX701 1 PY001 - PY008 1 PY021 - PY022 1 PY031 1 PY036 - PY037 1 PY046 - PY048 1 PY051 - PY053 1 PY056 - PY057 1 PY101 - PY103 1 PY111 - PY113 1 PY131 - PY135

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 20of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group**  **Variable Number** 1 PY141 - PY143 1 PY151 - PY154 1 PY156 - PY157 1 PY161 - PY162 1 PY166 1 PY191 1 PY201 1 PY221 - PY222 1 PY231 1 PY241 - PY244 1 PY270 - PY275 1 PY281 1 PY286 1 PY301 - PY304 1 PY321 - PY323 1 PY341 - PY346 1 PY361 - PY362 1 PY381 1 PY401 1 PY409 - PY411 1 PY421 - PY422 1 PY441 1 PY451 1 PY461 - PY463 1 PY591 - PY595 1 PY611 - PY612 1 PY621 1 PY631 1 PY651 1 PY671 - PY672 1 PY721 1 PY741

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 21of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**2. Spares Affected None. **B. Concurrent Requirements**  None. **C. Reason**  For airplanes that have not been inspected using the High Frequency Eddy Current (HFEC) open hole inspection in accordance with Service Bulletin (SB)737-57-1318, this SB gives instructions to do inspections for any crack in the inspar upper skin area near the rear spar at Wing Buttock Line (WBL) 157 until SB737-57-1318is accomplished. For an airplane that has not been inspected using the HFEC open hole inspection in accordance with SB737-57-1318, if the inspections in this service bulletin are not done, a crack in the upper chord and skin can grow undetected and result in the inability of the structure to carry limit load or result in a fuel leak and could prevent a continued safe flight and landing. While doing SB737-57-1318, an operator discovered a crack in the inspar upper skin at WBL 157 just forward of the rear spar on the right wing. The crack measured 2.375 inches long. Two additional cracks were found in the skin at two holes common to the rear spar in the same area. Subsequent inspections per SB737-57-1318revealed that the rear spar upper chord was almost completely severed. Further inspections per SB737-57-1318revealed that the left rear spar upper chord was completely severed. Web cracks were also discovered on both wings. The airplane was a 737-300 with 64,095 flight hours and 51,548 flight cycles. The airplane was within the 4,500 flight cycle grace period allowed by SB737-57-1318. The inspections in this SB will ensure there is no undetected crack in the inspar upper skin area near the rear spar at WBL 157 prior to the accomplishment of the inspections required by SB737-57-1318

. **D. Description**  Airplanes that have not been inspected using the HFEC open hole inspection in accordance with SB 737-57-1318, do an eddy current inspection for any crack in the inspar upper skin area near the rear spar at WBL 157. If a repair has been installed, do an eddy current inspection for any crack in the repair parts. If any crack is found, do the HFEC open hole inspection in accordance with SB737-57-1318 and contact Boeing for repair instructions and do the repair. The work in this service bulletin is done in the maintenance zone(s) given below. **Group 1:**
**Affected Maintenance Zones Zone**  **Model** 3-5, 4-5 737-100, 737-200, 737-200C

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 22of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group 1:** 
**Affected Maintenance Zones Zone**  **Model** 305, 405 737-300, 737-400, 737-500
**E. Compliance**  The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin mandatory. **Group 1, Configuration 1:** No action required. **Group 1, Configuration 2-7:** When more than one OPTION is given for a CONDITION, do only one of the OPTION numbers. When more than one ACTION is given for a CONDITION number or an OPTION number, do all of the ACTION numbers for that CONDITION number or OPTION number. **Group 1, Configuration 2-7:** Do the required actions in accordance with Paragraph 3. Accomplishment Instructions. **NOTE:** "Repair Parts" are defined as any combination of a repair doubler and repair tripler. **NOTE:** Boeing endorses the new FAA rules related to Limit of Validity (LOV) and recommends immediate and permanent removal from service of any airplane upon reaching the LOV, whether or not it is operated under FAA jurisdiction. As such, Boeing no longer provides maintenance instructions for airplanes that have accumulated flight cycles beyond the LOV. Line numbers 1-291 have accumulated flight cycles beyond the LOV of the airplane. 14 Code of Federal Regulations (CFR) Part 121.1115 and 129.115 prohibit operation of an airplane beyond its LOV. **Group 1, Configuration 2-4: Table 1: Eddy Current Inspection of Inspar Upper Skin Common to the Rear Spar at WBL 157**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Within 500 flight cycles after the Original Issuedate of this service bulletin. Before 30,000total flight cycles.Do PART 1: EDDY CURRENT INSPECTION for any crack in the insparupper skin and, if installed, the repair parts. All Airplanes.

- - - No further action re- quired. CONDITION 1: NO CRACK FOUND

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 23of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT Group 1, Configuration 2-4:** 

**Table 1: Eddy Current Inspection of Inspar Upper Skin Common to the Rear Spar at WBL 157 Repeat Interval**  **(Not to Exceed) Compliance Time (Whichever**  **Occurs Later) Action**  **Condition**

- Before further flight. ACTION 1: Do the HFEC open hole inspection in accordance with SB737- 57-1318

. CONDITION 2: ANY CRACK FOUND

- - Before further flight.ACTION 2: Contact Boeing for repair instructions and do the repair. **Group 1, Configuration 5-7: Table 2: Eddy Current Inspection of Inspar Upper Skin Common to the Rear Spar at WBL 157**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Within 500 flight cycles after the Original Issuedate of this service bulletin. Before 30,000total flight cycles.Do PART 1: EDDY CURRENT INSPECTION for any crack in the insparupper skin and, if installed, the repair parts. All Airplanes with 40,000 total flight cycles or less as of the Original Issue date of this service bulletin.

- Within 30 daysafter the Original Issue date ofthis service bulletin. - Do PART 1: EDDY CUR- RENT INSPECTION, for any crack in the insparupper skin and, if installed, the repair parts. All Airplanes with morethan 40,000 total flight cycles as of the Original Issue date of this service bulletin. 500 flight cycles. (a) - - Repeat PART 1: EDDYCURRENT INSPECTION, for any crack in the inspar upper skin and, if installed, the repair parts. CONDITION 1: NO CRACK FOUND

- Before further flight. ACTION 1: Do the HFEC open hole inspection in accordance with SB737- 57-1318

.(b) CONDITION 2: ANY CRACK FOUND

- - Before further flight.ACTION 2: Contact Boeing for repair instructions and do the repair. (a) Accomplishment of any inspection in accordance with SB737-57-1318terminates the repeat inspections in this SB. (b) Accomplishment of the HFEC open hole inspection in accordance with SB737-57-1318terminates the repeat inspections in this SB.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 24of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT F.**  **Approval** This service bulletin was examined by the Federal Aviation Administration (FAA). The changes specified in this service bulletin comply with the applicable regulations and are FAA approved, as well as European Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA approved airplanes listed in the service bulletin effectivity. This service bulletin and its approval were based on the airplane in its original Boeing delivery configuration or as modified by other approved Boeing changes. If an airplane has a non-Boeing modification or repair that affects a component or system also affected by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval before incorporating this service bulletin. **G. Manpower**  The table below shows an estimate of the task hours necessary to do this work for each airplane. This estimate is for direct labor only, done by an experienced crew. Adjust the estimate with operator task hour data if necessary. The estimate does not include lost time. These are some examples of lost time:

• Time to adjust to the workplace

• Time to schedule the work

• Time to inspect the work

• Time to cure the materials

• Time to make the parts

• Time to find the tools. **Group 1, Configuration 2, 5: Elapsed Hours**  **Task Hours Number of Persons**  **Task** 1.0 1.0 1 Figure 1 1.0 1.0 TOTAL FOR EACH AIRPLANE **Group 1, Configuration 3, 6: Elapsed Hours**  **Task Hours Number of Persons**  **Task** 1.0 1.0 1 Figure 2 1.0 1.0 TOTAL FOR EACH AIRPLANE **Group 1, Configuration 4, 7: Elapsed Hours**  **Task Hours Number of Persons**  **Task** 1.0 1.0 1 Figure 3 1.0 1.0 TOTAL FOR EACH AIRPLANE
**H. Weight and Balance Changes**  None.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 25of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT I.**  **Electrical Load Data**

Not changed. **J. References**  1. Existing Data:

a. Boeing Service Bulletin737-57-1318 b. Boeing Service Letter737-SL-51-042

c. Service Bulletin IndexD6-19567 d. 737 Non-Destructive Testing (NDT) ManualPart 6, 51-00-00 Procedure 4 or Procedure 23, Part 6, 51-00-26 2. Data Supplied with this Service Bulletin:

a. Drawings:
**ADCN DCN/REV**  **Sheet Title**  **Drawing No**

- - DWG UPPER REAR SPAR CHORD REINFORCE- MENT - RSS 224 65C30105

- - DWG SKIN REPAIR INSTL - UPPER, WBL 157.0, REAR SPAR TO S-4 65C30113

3. Installation Drawings Used in the Preparation of this Service Bulletin:
**Title Drawing Number**  WING SKIN 65C25204 REAR SPAR INSTALLATION - WING 65-45321 UPPER REAR SPAR CHORD REINFORCEMENT - RSS 224 65C30105 SKIN REPAIR INSTL - UPPER, WBL 157.0, REAR SPAR TO S-4 65C30113 The table above lists applicable drawings used to prepare this service bulletin. The drawings are not necessary to make the specified changes, and are not supplied with this service bulletin. The drawings may not be applicable to all airplane configurations or operators.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 26of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT K.**  **Publications Affected** 1. Publications: None. 2. Damage Tolerance Based Structural Inspections: Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the Maintenance Program. This service bulletin affects FCS but no new DTIs are necessary. **L. Interchangeability and Intermixability of Parts**  Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts. **M. Software Accomplishment Summary**  Not affected.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 27of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 28of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**

BLANK PAGE**2. MATERIAL INFORMATION A.**  **Material - Price and Availability** None. **B. Industry Support Information**  At the time of release of this service bulletin, warranty remedies have not been determined. A subsequent revision or Information Notice will address the warranty remedies available, if any. **C. Parts Necessary for Each Airplane**  1. Kits/Parts None. 2. Parts and Materials Supplied by the Operator No special parts or materials are necessary to do the change in this service bulletin. But, parts and materials in the manuals given inParagraph 1.J., References, can be necessary. Examine operator part and material supply to make sure all necessary parts and materials are available. 3. Parts Modified and Reidentified None. 4. Parts Removed and Not Replaced None. **D. Parts Necessary to Change Spares**  None. **E. Special Tooling - Price and Availability**  None. **F. Special Tooling Necessary to do this Service Bulletin**  No special tools or equipment are necessary to do the change in this service bulletin. But, maintenance and overhaul tools in the manuals given inParagraph 1.J., References, can be necessary. Examine operator tool supply to make sure all necessary tools are available.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 29of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 30of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**

BLANK PAGE**3. ACCOMPLISHMENT INSTRUCTIONS A.**  **GENERAL INFORMATION CAUTION:**  KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL

PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL, METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR OTHER ELECTRICAL DAMAGE. **NOTE:** 1. Manual titles are referred to by acronyms. Refer toParagraph 1.J., References, for

definition of the acronyms. 2. Obey all of the warnings and cautions given in the specified manual sections. 3. Unless shown differently, these dimensions and tolerances are used:

– Linear dimensions are in inches

– Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus or minus 0.03 inch

– Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch

– Angular tolerance is plus or minus 2 degrees

– Hole dimensions for standard solid rivets and fasteners are in Structural Repair Manual (SRM) Chapter 51

– Torque Values:

— Values for structural fasteners are given in 737 Structural Repair Manual, Chapter 51.

— Values for airframe maintenance tasks are included in Chapter 20 of 737 Aircraft Maintenance Manual (AMM).

— Non-standard torque values for maintenance tasks are included in the applicable installation step.

4. These work instructions refer to procedures included in other Boeing documents. When the words "refer to" are used and the operator has an accepted alternative procedure, the accepted alternative procedure can be used. When the words "in accordance with" are included in the instruction, the procedure in the Boeing document must be used. 5. Boeing Service Letter737-SL-51-042, Damage Reporting and Repair Plan/Design

Guidelines, is an acceptable procedure to request information from Boeing for additional structural repair instructions. The Service Letter describes what information must be provided to Boeing before a structural repair can be provided. 6. If it is necessary to remove more parts for access, you can remove those parts. If you can get access without removing identified parts, it is not necessary to remove all of the identified parts. Jacking and shoring limitations must be observed.
7. Use of colors in Figures is based on guidance from the ATA e-Business Program

(ATA) iSpec 2200.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 31of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**8. When more than one OPTION is given for a CONDITION, do only one of the OPTION numbers. When more than one ACTION is given for a CONDITION number or an OPTION number, do all of the ACTION numbers for that CONDITION number or OPTION number. 9. The compliance times for the actions in Paragraph 3.B., WORK INSTRUCTIONS are inParagraph 1.E., Compliance

. 10. Some steps in the Work Instructions are labeled as Required for Compliance (RC). If this service bulletin is mandated by an Airworthiness Directive (AD), then the steps labeled as RC, including sub-steps under an RC step and any figures identified in an RC step, must be done to comply with the AD. An Alternative Method of Compliance (AMOC) is required for any deviations to RC steps, including sub-steps and identified figures. Steps not labeled as RC may be deviated from using accepted methods in accordance with the operator's maintenance or inspection program without obtaining approval of an AMOC. This is provided that the RC steps, including sub-steps and identified figures, can still be done as specified, and the airplane can be put back in an airworthy condition. 11. "Repair Parts" are defined as any combination of a repair doubler and repair tripler. **B. WORK INSTRUCTIONS**  **Group 1, Configuration 2-7:** 1. RC - Do PART 1: EDDY CURRENT INSPECTION for any crack in the inspar upper skin, and if installed, the repair parts.

a. CONDITION 1: NO CRACK FOUND. (1) **Group 1, Configuration 2-4:** No further action required. (2) **Group 1, Configuration 5-7:** Repeat PART 1: EDDY CURRENT INSPECTION for any crack in the inspar upper skin, and if installed, the repair parts. **Group 1, Configuration 5-7: NOTE:**  Accomplishment of any inspection in accordance with SB737-57-1318terminates the repeat inspections in this SB. b. CONDITION 2: ANY CRACK FOUND. (1) ACTION 1: Do the High Frequency Eddy Current (HFEC) open hole inspection in accordance with Service Bulletin (SB)737-57-1318

. (2) ACTION 2: Contact Boeing for repair instructions and do the repair. **Group 1, Configuration 5-7: NOTE:**  Accomplishment of the HFEC open hole inspection in accordance with SB 737-57-1318terminates the repeat inspections in this SB. 2. Put the airplane back to a serviceable condition.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 32of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT PART 1: EDDY CURRENT INSPECTION**  1. **Group 1, Configuration 2, 5:** Do the inspections in accordance withFIGURE 1

. **Group 1, Configuration 3, 6:** Do the inspections in accordance withFIGURE 2

. **Group 1, Configuration 4, 7:** Do the inspections in accordance withFIGURE 3

.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 33of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT This Figure applies only to: Group 1, Configuration 2, 5.** 

**FIGURE 1: HFEC INSPECTION OF INSPAR UPPER SKIN AT REAR SPAR, WBL 157**  **(SHEET 1 OF 2)** Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 34of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
**More Data Qty**  **Identification Name**  **Task Step**  Do an HFEC inspection in accordance with737 NDT Manual Part 6, 51-00-00Procedure 4 or Procedure 23aroundthe fasteners indicated. - - Inspar Upper Skin Inspect 1

**FIGURE 1: HFEC INSPECTION OF INSPAR UPPER SKIN AT REAR SPAR, WBL 157**  **(SHEET 2 OF 2)** Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 35of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT This Figure applies only to: Group 1, Configuration 3, 6.** 

**FIGURE 2: HFEC INSPECTION OF INSPAR UPPER SKIN AND REPAIR DOUBLER AT REAR SPAR, WBL**  **157 (SHEET 1 OF 2)**  Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 36of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT More Data**  **Qty Identification**  **Name Task**  **Step** Do an HFEC inspection in accordance with737 NDT Manual Part 6, 51-00-00Procedure 4 or Procedure 23aroundthe fasteners indicated.(a) - - Inspar Upper Skin and Repair Doubler Inspect 1

Do an HFEC inspection in accordance with737 NDT Manual Part 6, 51-00-00Procedure 4 or Procedure 23along the forward edge of the repair doubler. - - Inspar Upper Skin Inspect 2

(a) It is a requirement that the repair doubler is the same material, thickness, and profile as repair drawing 65C30105

.

**FIGURE 2: HFEC INSPECTION OF INSPAR UPPER SKIN AND REPAIR DOUBLER AT REAR SPAR, WBL**  **157 (SHEET 2 OF 2)**  Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 37of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT This Figure applies only to: Group 1, Configuration 4, 7.** 

**FIGURE 3: HFEC AND LFEC INSPECTION OF INSPAR UPPER SKIN, REPAIR DOUBLER, AND REPAIR**  **TRIPLER AT REAR SPAR, WBL 157**

**(SHEET 1 OF 2)** Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 38of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT More Data**  **Qty Identification**  **Name Task**  **Step** Do an HFEC inspection in accordance with737 NDT Manual Part 6, 51-00-00Procedure 4 or Procedure 23aroundthe fasteners indicated.(a) - - Repair Tripler Inspect 1

Do a Low Frequency Eddy Current (LFEC) inspection in accordance with737 NDT Manual Part 6, 51-00-26around the fasteners indicated. (a) - - Repair Doubler Inspect 2

Do an HFEC inspection in accordance with737 NDT Manual Part 6, 51-00-00Procedure 4 or Procedure 23along the aft edge of the repair doubler. - - Inspar Upper Skin Inspect 3

(a) It is a requirement that the repair doubler and the repair tripler are the same material, thickness, and profile as repair drawing65C30113

.

**FIGURE 3: HFEC AND LFEC INSPECTION OF INSPAR UPPER SKIN, REPAIR DOUBLER, AND REPAIR**  **TRIPLER AT REAR SPAR, WBL 157**

**(SHEET 2 OF 2)** Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 22, 2015 737-57A1326 39of39 **BOEING SERVICE BULLETIN 737-57A1326 ALERT**  **ALERT**